In industrialized settings, power supplied to users is provided through a “power grid.” Such a grid often consists of power plants, transmission substations, high voltage transmission lines, power substations, transformers and couplings to the end users. A power grid is also a collection of power networks, where power is shared so that power needs in one area can be compensated for from power from another area. Redundant paths and lines are provided so that power can be routed from any power plant to any load center, through a variety of routes, based on the economics of the transmission path and the cost of power. Much analysis is done by transmission companies to determine the maximum reliable capacity of each line, which, due to system stability considerations, may be less than the physical or thermal limit of the line. Analysis of a power grid system is important to its continued use and the detection of power system disturbances, such as generator trips.
Frequency information can be used in many areas of power system analysis, operation, and control. Typically, only static frequency measurements are widely available. This is because most frequency measurement devices assume a single system frequency, and they use long periods of data averaging in order to achieve good estimation accuracy. This is not a problem when the system is in its steady state. However, the most valuable frequency data are those obtained during disturbances, when the system frequency is time varying, and when frequencies could be very different in different parts of the system. Accurate dynamic wide-area measured frequency is highly desirable, especially as blackout events are becoming increasingly severe in power systems around the world.
Power engineers have worked for decades to develop measurement tools for observing a power system's dynamics. For example, in the early 1990's the synchronized Phaser Measurement Unit (PMU) was developed and later commercialized. Since then, a number of applications have been proposed that require wide-area measurement systems.
The results of all earlier efforts clearly point to the need for much wider measurement coverage, coverage that can be quickly and economically obtained. One issue that constrains industry monitoring occurs because of power deregulation and restrictions on use of some power systems data. Energy trading companies and financial services corporations would likely benefit from great abilities to analyze the power grid.